Ridley Scott‘s The Martianis on the fast track. With a November 2015 release date fast approaching, it has to be. So we’ll surely be hearing more and more about the Cast Away meets Apollo 13 thriller in the coming weeks.

The director has already got Matt Damon to play the lead role of Mark Watney, a wisea-ss astronaut who is stranded on Mars. And now the trades are reporting Jessica Chastain and Kristen Wiig are circling “the female lead” of the film. However, the book most certainly doesn’t have a “female lead” so either the movie is radically different from the book or they’re just up for one of the several supporting, but equally awesome female characters in the film. Read more about The Martian casting below.

Variety posted about Chastain, and Deadline added Wiig’s name to the mix. Both suggest discussions are very early so nothing is set in stone.

So who could each actress play? There are some very excellent roles in the book, but to dive too deep into them would be kind of spoilerish. I’ll tread lightly.

In Weir’s book, we don’t only follow Watney. He’s about 80% of the story but we do get some outside perspective. We also follow some action on Earth at NASA and on the ship of astronauts who mistakenly leave him on Mars. That second place is most likely where the role is coming from, that of Commander Lewis. She’s a hard ass, respected leader of the crew with some big decisions to make and facts to face. If anyone is the “female lead,” it’s her. Chastain makes perfect sense for the role.

There’s also Mindy Park, an under utilized but important NASA employee who I could see Wiig playing. There’s head of public relations for NASA Annie Montrose and fellow astronaut Johanssen, a beautiful but nerdy character. All of these are very important to the story, and honestly, either actress could play any of those roles.

The question becomes, does the screenplay by Drew Goddard expand any of these? Is Chastain too big for a supporting role? Would she or Wiig to anything to work with Ridley Scott? We’ll definitely find out soon with the film in theaters in just over a year.